U.S. patent application number 16/626702 was filed with the patent office on 2020-05-21 for electric drive device and electric power steering device.
This patent application is currently assigned to HITACHI AUTOMOTIVE SYSTEMS, LTD.. The applicant listed for this patent is HITACHI AUTOMOTIVE SYSTEMS, LTD.. Invention is credited to Katsumasa HAGIWARA, Hideyuki HARA, Haruaki MOTODA, Kazuhiko NAKANO, Tetsuro TATEYAMA.
Application Number | 20200156696 16/626702 |
Document ID | / |
Family ID | 64740516 |
Filed Date | 2020-05-21 |
View All Diagrams
United States Patent
Application |
20200156696 |
Kind Code |
A1 |
HARA; Hideyuki ; et
al. |
May 21, 2020 |
ELECTRIC DRIVE DEVICE AND ELECTRIC POWER STEERING DEVICE
Abstract
The device has motor housing side annular engagement portion 40
formed at outer circumferential surface of end surface portion of
motor housing 11 which is opposite side to output shaft portion of
rotation shaft of electric motor; and metal cover side annular
engagement portion 38 formed at opening end 37 of metal cover 12
that covers electronic control unit and engaged with motor housing
side annular engagement portion 40. Fixing region is formed by
fixing metal cover side annular engagement portion 38 to motor
housing side annular engagement portion 40 in a fixing manner
without using any fixing screw in a state in which metal cover side
annular engagement portion 38 is engaged with motor housing side
annular engagement portion 40. Sealing region is formed between
fixing region and opening end 37 of the metal cover 12 with liquid
sealant 41 applied between fixing region and opening end 37.
Inventors: |
HARA; Hideyuki;
(Isesaki-shi, Gunma, JP) ; MOTODA; Haruaki;
(Isesaki-shi, Gunma, JP) ; NAKANO; Kazuhiko;
(Isesaki-shi, Gunma, JP) ; HAGIWARA; Katsumasa;
(Isesaki-shi, Gunma, JP) ; TATEYAMA; Tetsuro;
(Isesaki-shi, Gunma, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HITACHI AUTOMOTIVE SYSTEMS, LTD. |
Hitachinaka-shi, Ibaraki |
|
JP |
|
|
Assignee: |
HITACHI AUTOMOTIVE SYSTEMS,
LTD.
Hitachinaka-shi, Ibaraki
JP
|
Family ID: |
64740516 |
Appl. No.: |
16/626702 |
Filed: |
March 7, 2018 |
PCT Filed: |
March 7, 2018 |
PCT NO: |
PCT/JP2018/008700 |
371 Date: |
December 26, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 11/33 20160101;
B62D 6/10 20130101; B62D 5/0409 20130101; B62D 5/0484 20130101;
B62D 5/04 20130101; H02K 5/225 20130101; H02K 5/10 20130101; B62D
5/0463 20130101; B62D 5/0406 20130101 |
International
Class: |
B62D 5/04 20060101
B62D005/04; H02K 11/33 20060101 H02K011/33; B62D 6/10 20060101
B62D006/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2017 |
JP |
2017-126136 |
Claims
1. An electric drive device comprising: a metal-made motor housing
accommodating therein an electric motor that drives a mechanical
control element; an electronic control unit provided at an end
surface portion side of the motor housing which is an opposite side
to an output shaft portion of a rotation shaft of the electric
motor and having a control circuit unit, a power supply circuit
unit and a power conversion circuit unit that are configured to
drive the electric motor; and a metal-made metal cover covering the
electronic control unit, and wherein a motor housing side annular
engagement portion is formed on an outer circumferential surface of
the end surface portion of the motor housing which is the opposite
side to the output shaft portion of the rotation shaft of the
electric motor, a metal cover side annular engagement portion that
is engaged with the motor housing side annular engagement portion
is formed at an opening end of the metal cover, a fixing region is
formed by fixing the metal cover side annular engagement portion to
the motor housing side annular engagement portion in a fixing
manner without using any fixing screw in a state in which the metal
cover side annular engagement portion is engaged with the motor
housing side annular engagement portion, and a sealing region is
formed between the fixing region and the opening end of the metal
cover with a liquid sealant applied between the fixing region and
the opening end of the metal cover.
2. The electric drive device as claimed in claim 1, wherein: the
fixing region is formed by pressing and squeezing a wall surface of
the metal cover side annular engagement portion against and into a
caulking recessed portion that is formed at the motor housing side
annular engagement portion and caulking the wall surface of the
metal cover side annular engagement portion.
3. The electric drive device as claimed in claim 2, wherein: the
caulking recessed portion provided at the motor housing side
annular engagement portion is formed on an entire circumferential
surface of the motor housing side annular engagement portion, or a
plurality of caulking recessed portions are formed at predetermined
positions on the circumferential surface of the motor housing side
annular engagement portion.
4. The electric drive device as claimed in claim 2, wherein: a
space formed at the sealing region in the state in which the metal
cover side annular engagement portion is engaged with the motor
housing side annular engagement portion is filled with the liquid
sealant.
5. The electric drive device as claimed in claim 4, wherein: an
annular groove that is recessed to an inner circumferential side is
formed on the circumferential surface, located at an opening end
side of the metal cover when viewed from the caulking recessed
portion, of the motor housing side annular engagement portion, and
the annular groove is filled with the liquid sealant.
6. The electric drive device as claimed in claim 5, wherein: a
bending portion is formed at the opening end of the metal cover by
at least two cutting portions, and the bending portion is engaged
with a wall surface of the annular groove by being bent.
7. The electric drive device as claimed in claim 6, wherein: a
plurality of bending portions provided at the opening end of the
metal cover are formed at positions corresponding to the caulking
recessed portions formed at the predetermined positions on the
circumferential surface of the motor housing side annular
engagement portion.
8. The electric drive device as claimed in claim 1, wherein: the
fixing region is formed by press-fitting or shrink-fitting the
metal cover side annular engagement portion to the motor housing
side annular engagement portion.
9. The electric drive device as claimed in claim 8, wherein: an
accommodating groove that accommodates therein the opening end of
the metal cover is formed at the motor housing side annular
engagement portion, the opening end of the metal cover is
accommodated in the accommodating groove, and the liquid sealant
fills the accommodating groove so as to encircle the opening end
from outside.
10. An electric power steering device comprising: an electric motor
providing a steering assistive force to a steering shaft on the
basis of an output from a torque sensor that detects a turning
direction and a turning torque of the steering shaft; an
aluminum-based metal-made motor housing accommodating therein the
electric motor; an electronic control unit provided at an end
surface portion side of the motor housing which is an opposite side
to an output shaft portion of a rotation shaft of the electric
motor and having a control circuit unit, a power supply circuit
unit and a power conversion circuit unit that are configured to
drive the electric motor; and a metal-made metal cover covering the
electronic control unit, and wherein a motor housing side annular
engagement portion is formed on an outer circumferential surface of
the end surface portion of the motor housing which is the opposite
side to the output shaft portion of the rotation shaft of the
electric motor, a metal cover side annular engagement portion that
is engaged with the motor housing side annular engagement portion
is formed at an opening end of the metal cover, a fixing region is
formed by fixing the metal cover side annular engagement portion to
the motor housing side annular engagement portion in a fixing
manner without using any fixing screw in a state in which the metal
cover side annular engagement portion is engaged with the motor
housing side annular engagement portion, and a sealing region is
formed between the fixing region and the opening end of the metal
cover with a liquid sealant applied between the fixing region and
the opening end of the metal cover.
11. The electric power steering device as claimed in claim 10,
wherein: the fixing region is formed by pressing and squeezing a
wall surface of the metal cover side annular engagement portion
against and into a caulking recessed portion that is formed at the
motor housing side annular engagement portion and caulking the wall
surface of the metal cover side annular engagement portion.
12. The electric power steering device as claimed in claim 11,
wherein: the caulking recessed portion provided at the motor
housing side annular engagement portion is formed on an entire
circumferential surface of the motor housing side annular
engagement portion, or a plurality of caulking recessed portions
are formed at predetermined positions on the circumferential
surface of the motor housing side annular engagement portion.
13. The electric power steering device as claimed in claim 11,
wherein: a space formed at the sealing region in the state in which
the metal cover side annular engagement portion is engaged with the
motor housing side annular engagement portion is filled with the
liquid sealant.
14. The electric power steering device as claimed in claim 13,
wherein: an annular groove that is recessed to an inner
circumferential side is formed on the circumferential surface,
located at an opening end side of the metal cover when viewed from
the caulking recessed portion, of the motor housing side annular
engagement portion, and the annular groove is filled with the
liquid sealant.
15. The electric power steering device as claimed in claim 14,
wherein: a bending portion is formed at the opening end of the
metal cover by at least two cutting portions, and the bending
portion is engaged with a wall surface of the annular groove by
being bent.
16. The electric power steering device as claimed in claim 15,
wherein: a plurality of bending portions provided at the opening
end of the metal cover are formed at positions corresponding to the
caulking recessed portions formed at the predetermined positions on
the circumferential surface of the motor housing side annular
engagement portion.
17. The electric power steering device as claimed in claim 10,
wherein: the fixing region is formed by press-fitting or
shrink-fitting the metal cover side annular engagement portion to
the motor housing side annular engagement portion.
18. The electric power steering device as claimed in claim 17,
wherein: an accommodating groove that accommodates therein the
opening end of the metal cover is formed at the motor housing side
annular engagement portion, the opening end of the metal cover is
accommodated in the accommodating groove, and the liquid sealant
fills the accommodating groove so as to encircle the opening end
from outside.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electric drive device
and an electric power steering device, and more particularly to an
electric drive device and an electric power steering device in
which an electronic control device is mounted.
BACKGROUND ART
[0002] In a field of general industrial equipment, a mechanical
control element is driven by an electric motor. In recent years,
so-called electrically mechanically integrated electric drive
device, which is configured such that an electronic control unit
formed from a semiconductor element etc. controlling a rotation
speed and/or a rotation torque of the electric motor is integrally
mounted in the electric motor, has been used.
[0003] As an example of the electrically mechanically integrated
electric drive device, for instance, an electric power steering
device is configured such that a turning direction and a turning
torque of a steering shaft that turns by driver's operation of a
steering wheel are detected, and on the basis of these detection
values, the electric motor is driven so as to rotate in the same
direction as the turning direction of the steering shaft, then a
steering assist torque is generated. To control this electric
motor, the power steering device is provided with an electronic
control unit (ECU: Electronic Control Unit).
[0004] As a related art electric power steering device, for
instance, an electric power steering device disclosed in Japanese
Unexamined Patent Application Publication No. 2015-134598 (Patent
Document 1) is known. Patent Document 1 discloses the electric
power steering device configured by an electric motor unit and an
electronic control unit. An electric motor of the electric motor
unit is housed in a motor housing having a cylindrical portion made
of aluminum alloy etc. A board of the electronic control unit on
which electronic elements or components are mounted is fixed to a
heat sink that is located at an opposite side to an output shaft of
the electric motor in an axial direction of the motor housing and
serves as an ECU housing.
[0005] The board fixed to the heat sink mounts thereon a power
supply circuit unit, a power conversion circuit unit having a power
switching element such as a MOSFET and an IGBT that drive and
control the electric motor, and a control circuit unit that
controls the power switching element. An output terminal of the
power switching element and an input terminal of the electric motor
are electrically connected through a bus bar.
[0006] Power is supplied to the electronic control unit fixed to
the heat sink from a power supply through a connector case made of
synthetic resin. Further, detection signals concerning an operating
state etc. are sent to the electronic control unit from detection
sensors. The connector case functions as a lid member or a cover
member, and is fixed to an outer peripheral surface of the heat
sink with a fixing screw so as to hermetically seal the heat
sink.
[0007] As another electric drive device in which the electronic
control device is integrally mounted, an electric brake and an
electric hydraulic pressure controller for various kinds of
hydraulic pressure control are known. In the following description,
the electric power steering device from among these electric drive
devices will be explained.
CITATION LIST
Patent Document
[0008] Patent Document 1: Japanese Unexamined Patent Application
Publication No. 2015-134598
SUMMARY OF THE INVENTION
Technical Problem
[0009] In a case of the configuration of the electric power
steering device disclosed in Patent Document 1, the motor housing,
the heat sink and the connector case are connected to each other
with fixing screws inserted and screwed into fixing portions that
are formed at respective outer peripheral sides of the motor
housing, the heat sink and the connector case so as to protrude
outwards.
[0010] Further, sealing members such as an O-ring to ensure
liquid-tightness are used between the motor housing and the heat
sink and between the heat sink and the connector case. As mentioned
above, the motor housing and the heat sink, and the heat sink and
the connector case, are connected with the fixing screws. Here, in
a case where the heat sink is not used, the motor housing and the
connector case are connected with the fixing screws with the O-ring
interposed between the motor housing and the connector case.
[0011] Here, vehicles are also used in a region where the vehicles
severely suffer from salt damage. In a case of a liquid tightness
sealing structure by only the O-ring, however, a fitting gap
substantially appears in an area where the O-ring is provided.
Because of this, there is a possibility that salt water will get in
this fitting gap and will rust an O-ring accommodating portion.
Further, at the worst, this causes poor liquid tightness, and the
salt water further gets inside, then there is a risk that
electrical reliability will be lost.
[0012] In addition, when the fixing portions and the fixing screws
are provided at the outer peripheral sides of the motor housing,
the heat sink and the connector case, there is a risk that
mechanical reliability will be lost due to reduction in a fixing
strength by rust of the fixing screw. And also, this configuration
has a problem of increasing an outward appearance size and a
weight.
[0013] Therefore, an electric drive device and an electric power
steering device that are capable of resolving these problems are
required.
[0014] Additionally, in the electric power steering device
disclosed in Patent Document 1, the heat sink to release heat of,
especially, the power supply circuit unit and the power conversion
circuit unit is arranged between the motor housing and the ECU
housing. For this reason, a length in an axial direction tends to
become longer by a size of the heat sink. Further, since an
electrical component forming the power supply circuit unit and the
power conversion circuit unit has a large heat value, when
achieving size reduction, this heat has to be efficiently radiated
or released to the outside. Accordingly, it is required for the
axial direction length of the electric drive device to be as short
as possible, and also it is required for the heat of the power
supply circuit unit and the power conversion circuit unit to be
efficiently radiated or released to the outside.
[0015] A main object of the present invention is therefore to
provide a new electric drive device and a new electric power
steering device that are capable of improving the mechanical and
electrical reliability and reducing the outward appearance size and
the weight.
Solution to Problem
[0016] The present invention has, as features, a motor housing side
annular engagement portion formed on an outer circumferential
surface of an end surface portion of a metal-made motor housing
which is an opposite side to an output shaft portion of a rotation
shaft of an electric motor; and a metal cover side annular
engagement portion formed at an opening end of a metal cover that
covers an electronic control unit configured to control the
electric motor and engaged with the motor housing side annular
engagement portion, and a fixing region is formed by fixing the
metal cover side annular engagement portion to the motor housing
side annular engagement portion in a fixing manner without using
any fixing screw in a state in which the metal cover side annular
engagement portion is engaged with the motor housing side annular
engagement portion, and a sealing region is formed between the
fixing region and the opening end of the metal cover with a liquid
sealant applied between the fixing region and the opening end of
the metal cover.
Effects of Invention
[0017] According to the present invention, since the sealing region
is formed between the fixing region and the opening end of the
metal cover with the liquid sealant applied between the fixing
region and the opening end of the metal cover, salt water etc. are
prevented from getting in the fixing region, then mechanical and
electrical reliability can be improved. Further, since the fixing
screw is not used, it is possible to reduce an outward appearance
size and a weight.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a general perspective view of a steering device as
an example to which the present invention is applied.
[0019] FIG. 2 is a general perspective view of an electric power
steering device according to an embodiment of the present
invention.
[0020] FIG. 3 is a perspective exploded view of the electric power
steering device shown in FIG. 2.
[0021] FIG. 4 is a perspective view of a motor housing shown in
FIG. 3.
[0022] FIG. 5 is a cross section of the motor housing shown in FIG.
4, which is cut in an axial direction of the motor housing.
[0023] FIG. 6 is a perspective view of the motor housing shown in
FIG. 4 with a power conversion circuit unit mounted on the motor
housing.
[0024] FIG. 7 is a perspective view of the motor housing shown in
FIG. 6 with a power supply circuit unit further mounted on the
motor housing.
[0025] FIG. 8 is a perspective view of the motor housing shown in
FIG. 7 with a control circuit unit further mounted on the motor
housing.
[0026] FIG. 9 is a perspective view of the motor housing shown in
FIG. 8 with a connector terminal assembly further mounted on the
motor housing.
[0027] FIG. 10 is a front view of the electric power steering
device after a caulking or swaging fixation is performed, according
to a first embodiment of the present invention.
[0028] FIG. 11 is a cross section of the electric power steering
device shown in FIG. 10 after the caulking or swaging fixation is
performed.
[0029] FIG. 12 is an enlarged local sectional view, cut in the
axial direction, of an engagement portion between the motor housing
and a metal cover and its vicinity after the caulking or swaging
fixation is performed.
[0030] FIG. 13 is an enlarged view of a part P of FIG. 12.
[0031] FIG. 14 is a top view, viewed from the connector terminal
assembly side, of the electric power steering device shown in FIG.
12.
[0032] FIG. 15 is an enlarged sectional perspective view of the
electric power steering device after a caulking or swaging fixation
is performed, according to a second embodiment of the present
invention.
[0033] FIG. 16 is an enlarged sectional view of the electric power
steering device shown in FIG. 15 after the caulking or swaging
fixation is performed.
[0034] FIG. 17 is an enlarged sectional perspective view of the
electric power steering device after a shrink-fitting fixation is
performed, according to a third embodiment of the present
invention.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0035] An embodiment of the present invention will be explained in
detail below with reference to the drawings. The present invention
is not limited to the following embodiment, and includes all design
modifications and equivalents belonging to the technical scope of
the present invention.
[0036] Before explaining the embodiment of the present invention, a
configuration of a steering device as an example to which the
present invention is applied will be briefly explained using FIG.
1.
[0037] First, a steering device to steer front wheels of a vehicle
will be explained. A steering device 1 is configured as shown in
FIG. 1. A pinion (not shown) is provided at a lower end of a
steering shaft 2 connecting to a steering wheel (not shown). This
pinion is engaged with a rack (not shown) that extends in right and
left directions of a vehicle body. A tie rod 3 to steer the front
wheels in the right and left directions is each connected to both
ends of the rack. The rack is accommodated in a rack housing 4.
Between the rack housing 4 and each tie rod 3, a rubber boot 5 is
provided.
[0038] The steering device 1 is provided with an electric power
steering device 6 to assist torque when performing a turning
operation of the steering wheel. That is, a torque sensor 7 that
detects a turning direction and a turning torque of the steering
shaft 2 is provided. And, an electric motor unit 8 that provides a
steering assistive force to the rack via a gear 10 on the basis of
a detection value of the torque sensor 7 is provided. Further, an
electronic control unit (ECU) 9 that controls an electric motor
disposed in the electric motor unit 8 is provided. The electric
motor unit 8 of the electric power steering device 6 is connected
to the gear 10 at three portions of an outer periphery at an output
shaft side of the electric motor unit 8 with screws (not shown).
The electronic control unit 9 is disposed on an opposite side to
the output shaft side of the electric motor unit 8.
[0039] In the electric power steering device 6, when the steering
shaft 2 is turned in any turning direction by the steering wheel
operation, the torque sensor 7 detects the turning direction and
the turning torque of the steering shaft 2. A control circuit unit
calculates a drive operation amount of the electric motor on the
basis of these detection values. The electric motor is then driven
by a power switching element of a power conversion circuit unit on
the basis of the calculated drive operation amount. And, an output
shaft of the electric motor rotates so as to drive and rotate the
steering shaft 2 in the same direction as a direction of the
steering wheel operation. This rotation of the output shaft of the
electric motor is transmitted to the rack (not shown) through the
pinion (not shown) and the gear 10, and the vehicle is steered.
Since such configuration and workings are well known, a further
explanation will be omitted here.
[0040] As mentioned above, vehicles are also used in the region
where the vehicles severely suffer from salt damage, and in the
case of the liquid tightness sealing structure by only the O-ring
like the electric power steering device having the configuration
disclosed in Patent Document 1, the fitting gap substantially
appears in the area where the O-ring is provided. Because of this,
there is a possibility that salt water will get in this fitting gap
and will rust the O-ring accommodating portion. Further, at the
worst, this causes poor liquid tightness, and the salt water
further gets inside, then there is a risk that electrical
reliability will be lost.
[0041] In addition, when the fixing portions and the fixing screws
are provided at the outer peripheral sides of the motor housing,
the heat sink and the connector case, there is a risk that
mechanical reliability will be lost due to reduction in a fixing
strength by rust of the fixing screw. And also, this configuration
has a problem of increasing an outward appearance size and a
weight.
[0042] From such background, the present embodiment proposes the
electric power steering device having the following
configuration.
First Embodiment
[0043] In the present embodiment, the electric power steering
device has a motor housing side annular engagement portion formed
on an outer circumferential surface of an end surface portion of a
metal-made motor housing which is an opposite side to an output
shaft portion of a rotation shaft of an electric motor; and a metal
cover side annular engagement portion formed at an opening end of a
metal cover that covers an electronic control unit configured to
control the electric motor and engaged with the motor housing side
annular engagement portion. And, a fixing region is formed by
fixing the metal cover side annular engagement portion to the motor
housing side annular engagement portion in a fixing manner without
using any fixing screw in a state in which the metal cover side
annular engagement portion is engaged with the motor housing side
annular engagement portion, and a sealing region is formed between
the fixing region and the opening end of the metal cover with a
liquid sealant applied between the fixing region and the opening
end of the metal cover.
[0044] According to the above configuration, since the sealing
region is formed between the fixing region and the opening end of
the metal cover with the liquid sealant applied between the fixing
region and the opening end of the metal cover, salt water etc. are
prevented from getting in the fixing region, then mechanical and
electrical reliability can be improved. Further, since the fixing
screw is not used, it is possible to reduce an outward appearance
size and a weight. In addition, in a case where an O-ring is used,
it is required to form an accommodating groove for accommodating
the O-ring. However, in the present embodiment, since the O-ring is
not used, no machining for the accommodating groove is required,
and this can suppress increase in manufacturing cost.
[0045] In the following description, a configuration of the
electric power steering device according to a first embodiment of
the present invention will be explained in detail with reference to
FIGS. 2 to 14.
[0046] FIG. 2 is a drawing showing a general configuration of the
electric power steering device according to the present embodiment.
FIG. 3 is a drawing, viewed from an oblique direction, with
components of the electric power steering device shown in FIG. 2
dismantled. FIGS. 4 to 9 are drawings showing assembly states of
components that are assembled in an assembly order.
[0047] FIG. 10 is a drawing showing the whole of the electric power
steering device after a caulking or swaging fixation is performed.
FIG. 11 is a cross section of the electric power steering device
after the caulking or swaging fixation is performed. FIG. 12 is a
sectional view, cut in an axial direction, of an engagement portion
between a motor housing and a metal cover and its vicinity. FIG. 13
is an enlarged sectional view of a caulk-fixing portion (or a
swage-fixing portion) FIG. 14 is a drawing showing the metal cover,
viewed from a connector side. The embodiment will be explained
below with reference to the drawings.
[0048] As shown in FIG. 2, an electric motor unit 8 forming the
electric power steering device is configured by a motor housing 11
having a cylindrical portion made of aluminum or aluminum-based
metal such as aluminum alloy and an electric motor (not shown)
accommodated in the motor housing 11. An electronic control unit 9
is configured by a metal cover 12 made of aluminum, aluminum-based
metal such as aluminum alloy or iron-based metal and located at an
opposite side to an output shaft of the electric motor in an axial
direction of the motor housing 11 and an electronic control
assembly (not shown) accommodated in this metal cover 12.
[0049] The motor housing 11 and the metal cover 12 are fixedly
connected to each other at a fixing region FR that is formed at
their opposing end surfaces in an outer circumferential direction
by an after-described "caulking or swaging fixation". The
electronic control assembly accommodated inside the metal cover 12
is configured by a power supply circuit unit that generates a
required power, a power conversion circuit unit having a power
switching element such as a MOSFET and an IGBT that drive and
control the electric motor of the electric motor unit 8, and a
control circuit unit that controls the power switching element. An
output terminal of the power switching element and an input
terminal of a coil of the electric motor are electrically connected
through a bus bar.
[0050] A connector terminal assembly 13 is exposed from a hole
portion formed at an end surface, which is located at an opposite
side to the motor housing 11, of the metal cover 12. The connector
terminal assembly 13 is fixed to fixing portions formed at the
motor housing 11 with fixing screws. The connector terminal
assembly 13 has a connector terminal forming portion 13A for power
supply, a connector terminal forming portion 13B for detection
sensors, and a connector terminal forming portion 13C for control
state output by which a control state is outputted to an external
device.
[0051] The electronic control assembly accommodated in the metal
cover 12 is supplied with power from a power supply through the
synthetic-resin-made connector terminal forming portion 13A for
power supply. Further, the electronic control assembly is provided
with detection signals of an operating condition etc from the
detection sensors through the connector terminal forming portion
13B for detection sensors. A current control state signal of the
electric power steering device is outputted from the electronic
control assembly through the connector terminal forming portion 13C
for control state output.
[0052] FIG. 3 is a perspective exploded view of the electric power
steering device 6. An iron-made annular side yoke (not shown) is
fitted to an inside of a motor housing 11. The electric motor is
accommodated inside this side yoke. An output shaft portion 14 of
the electric motor provides the steering assistive force to the
rack via the gear. Since a specific structure of the electric motor
is well known, its explanation will be omitted here.
[0053] The motor housing 11 is made of aluminum alloy, and acts as
a heat sink that radiates or releases heat generated at the
electric motor and heat generated in after-mentioned power supply
circuit unit and power conversion circuit unit to the outside
atmosphere. The electric motor and the motor housing 11 form the
electric motor unit 8.
[0054] An electronic control unit EC is connected to an end surface
portion 15 of the motor housing 11 which is an opposite side to the
output shaft portion 14 of the electric motor unit 8. The
electronic control unit EC has the power conversion circuit unit
16, the power supply circuit unit 17, the control circuit unit 18
and the connector terminal assembly 13. The end surface portion 15
of the motor housing 11 is formed integrally with the motor housing
11. However, the end surface portion 15 could be formed separately
from the motor housing 11, then fixed to the motor housing 11 with
screws or by welding.
[0055] Here, the power conversion circuit unit 16, the power supply
circuit unit 17 and the control circuit unit 18 form a redundant
system (a dual-redundancy system) by a main electronic control unit
and a sub-electronic control unit. In a normal condition, the
electric motor is driven and controlled by the main electronic
control unit. However, if an abnormal condition or a failure occurs
at the main electronic control unit, the control is switched to the
sub-electronic control unit, and the electric motor is driven and
controlled by the sub-electronic control unit.
[0056] Therefore, normally, heat from the main electronic control
unit is transmitted to the motor housing 11. If the abnormal
condition or the failure occurs at the main electronic control
unit, the main electronic control unit stops and the sub-electronic
control unit operates, then heat from the sub-electronic control
unit is transmitted to the motor housing 11. These will be
described later.
[0057] However, both of the main electronic control unit and the
sub-electronic control unit could operate as a regular electronic
control unit, although the present invention does not apply this
configuration. And, if the abnormal condition or the failure occurs
at one of the electronic control units, the other electronic
control unit drives and controls the electric motor by half
ability. In this case, although capability of the electric motor is
half, so-called limp-home function is secured. Therefore, in the
normal condition, heat from the main electronic control unit and
the sub-electronic control unit is transmitted to the motor housing
11.
[0058] The electronic control unit EC is configured by the power
conversion circuit unit 16, the power supply circuit unit 17, the
control circuit unit 18 and the connector terminal assembly 13.
These power conversion circuit unit 16, power supply circuit unit
17, control circuit unit 18 and connector terminal assembly 13 are
arranged in this order from the end surface portion 15 side to a
direction moving away from the end surface portion 15. The control
circuit unit 18 is a unit that generates a control signal for
driving the switching element of the power conversion circuit unit
16, and is configured by a microcomputer and a peripheral circuit
and so on. The power supply circuit unit 17 is a unit that
generates power to drive the control circuit unit 18 and power for
the power conversion circuit unit 16, and is configured by a
capacitor, a coil and a switching element and so on. The power
conversion circuit unit 16 is a unit that controls power (current)
flowing in the coil of the electric motor, and is configured by a
switching element that forms three-phase upper and lower arms and
so on.
[0059] A unit having a large heat value in the electronic control
unit EC is mainly the power conversion circuit unit 16 and the
power supply circuit unit 17. Heat of the power conversion circuit
unit 16 and the power supply circuit unit 17 is released from the
motor housing 11 made of aluminum alloy. This detailed structure or
configuration will be described with reference to FIGS. 4 to 9
later.
[0060] The synthetic-resin-made connector terminal assembly 13 is
arranged between the control circuit unit 18 and the metal cover
12, and is connected to a vehicle battery (the power supply) and
other external control device (not shown). Needless to say, the
connector terminal assembly 13 is connected to the power conversion
circuit unit 16, the power supply circuit unit 17 and the control
circuit unit 18.
[0061] The metal cover 12 has a function of accommodating and
liquid-tightly sealing the power conversion circuit unit 16, the
power supply circuit unit 17 and the control circuit unit 18. In
the present embodiment, the metal cover 12 is fixed to the motor
housing 11 by the caulking or swaging fixation.
[0062] Although details about this caulking or swaging fixation of
the metal cover 12 to the motor housing 11 is explained later, a
motor housing side annular engagement portion and a metal cover
side annular engagement portion formed at an opening end of the
metal cover 12 and engaged with the motor housing side annular
engagement portion are formed. And, a fixing region is formed by
fixing the metal cover side annular engagement portion to the motor
housing side annular engagement portion by caulking or swaging
fixation (which is a fixing manner without using any fixing screw)
in a state in which the metal cover side annular engagement portion
is engaged with the motor housing side annular engagement portion,
and a sealing region is formed between the fixing region and the
opening end of the metal cover with a liquid sealant applied
between the fixing region and the opening end of the metal
cover.
[0063] According to this configuration, since the sealing region is
formed between the fixing region and the opening end of the metal
cover with the liquid sealant applied between the fixing region and
the opening end of the metal cover, salt water etc. are prevented
from getting in the fixing region, then mechanical and electrical
reliability can be improved. Further, since the fixing screw is not
used, it is possible to reduce an outward appearance size and a
weight.
[0064] Next, structure or configuration of each component and an
assembling method of the components will be explained with
reference to FIGS. 4 to 9. FIG. 4 is an external view of the motor
housing 11. FIG. 5 is a cross section of the motor housing 11,
which is cut in an axial direction of the motor housing 11.
[0065] In FIGS. 4 and 5, the motor housing 11 is shaped into a
cylindrical or tubular shape. The motor housing 11 has a side
peripheral surface portion 11A, the end surface portion 15 that
closes one end of the side peripheral surface portion 11A and an
end surface portion 19 that closes the other end of the side
peripheral surface portion 11A. In the present embodiment, the side
peripheral surface portion 11A and the end surface portion 15 are
formed integrally with each other, then the motor housing 11 has a
bottomed cylindrical shape. The end surface portion 19 serves as a
lid, and closes the other end of the side peripheral surface
portion 11A after accommodating the electric motor in the side
peripheral surface portion 11A.
[0066] An annular step portion (=the motor housing side annular
engagement portion) 35 whose diameter is reduced inwards in a
radial direction is formed at an outer circumferential surface of
the end surface portion 15. Then, the opening end (=the metal cover
side annular engagement portion) 37 of the metal cover 12 shown in
FIG. 9 is engaged with this step portion 35. A fixing manner
between the step portion 35 and the opening end 37 of the metal
cover 12 is a fixing manner called the caulking or swaging
fixation. This fixing manner will be explained later.
[0067] As shown in FIG. 5, a stator 21 having cores around which
coils 20 are wound is fitted in the side peripheral surface portion
11A of the motor housing 11, and a rotor 22 in which a permanent
magnet is embedded is rotatably accommodated inside this stator 21.
A rotation shaft 23 is fixed to the rotor 22, and its one end is
the output shaft portion 14, and its other end is a rotation
detection portion 24 for detecting a rotation phase and a rotation
speed of the rotation shaft 23. The rotation detection portion 24
is provided with a permanent magnet, and protrudes to the outside
through a penetration hole 25 formed at the end surface portion 15.
The rotation phase and the rotation speed of the rotation shaft 23
are detected by a magnetism detecting portion configured by a GMR
element (not shown) etc.
[0068] Returning to FIG. 4, heat radiating sections (heat releasing
sections) 15A and 15B for the power conversion circuit unit 16 (see
FIG. 3) and the power supply circuit unit 17 (see FIG. 3) are
formed on a surface of the end surface portion 15 located at an
opposite side to the output shaft portion 14 of the rotation shaft
23. Further, board-connector fixing protrusions 26 are formed
integrally with the end surface portion 15 at four corners of the
end surface portion 15 so as to stand on or protrude from the
surface of the end surface portion 15. Each board-connector fixing
protrusion 26 has a screw hole inside the board-connector fixing
protrusion 26. The board-connector fixing protrusion 26 is provided
to secure an after-mentioned circuit board of the control circuit
unit 18 and also the connector terminal assembly 13. The
board-connector fixing protrusions 26 protruding from the
power-conversion-circuit heat releasing section 15A (described
later) each have a board receiving portion 27 whose height in the
axial direction is the same as that of the power-supply-circuit
heat releasing section 15B (described later). This board receiving
portion 27 is a portion which an after-mentioned glass epoxy
circuit board 31 of the power supply circuit unit 17 is mounted on
and fixed to.
[0069] A plane area forming the end surface portion 15, which is
orthogonal to the rotation shaft 23, is sectioned off into two
sections. One is the power-conversion-circuit heat releasing
section 15A to which the power conversion circuit unit 16 having
the power switching element such as the MOSFET is fixed, and the
other is the power-supply-circuit heat releasing section 15B to
which the power supply circuit unit 17 is fixed. In the present
embodiment, an area of the power-conversion-circuit heat releasing
section 15A is greater than that of the power-supply-circuit heat
releasing section 15B. This is because that the redundant system is
employed as described above and a mounting area of the power
conversion circuit unit 16 is secured.
[0070] And, a different height step in the axial direction (a
direction in which the rotation shaft 23 extends) is provided
between the power-conversion-circuit heat releasing section 15A and
the power-supply-circuit heat releasing section 15B. That is, the
power-supply-circuit heat releasing section 15B is formed so as to
have a step that is away from the power-conversion-circuit heat
releasing section 15A in the direction of the rotation shaft 23 of
the electric motor. This step is set to such a height that the
power conversion circuit unit 16 and the power supply circuit unit
17 do not interfere with each other when the power supply circuit
unit 17 is mounted after the power conversion circuit unit 16 is
mounted.
[0071] The power-conversion-circuit heat releasing section 15A is
provided with three long narrow rectangular protruding heat
releasing portions 28. These protruding heat releasing portions 28
are portions on which the power conversion circuit unit 16 for the
redundant system is mounted. The protruding heat releasing portions
28 protrude from the surface of the power-conversion-circuit heat
releasing section 15A in the direction of the rotation shaft 23 of
the electric motor so as to be away from the electric motor.
[0072] The power-supply-circuit heat releasing section 15B is
formed into a flat surface, and the power supply circuit unit 17 is
mounted on the power-supply-circuit heat releasing section 15B.
Therefore, the protruding heat releasing portion 28 acts as a heat
releasing portion that releases and transmits heat generated at the
power conversion circuit unit 16 to the end surface portion 15, and
the power-supply-circuit heat releasing section 15B acts as a heat
releasing portion that releases and transmits heat generated at the
power supply circuit unit 17 to the end surface portion 15.
[0073] The protruding heat releasing portions 28 might be removed.
In this case, the power-conversion-circuit heat releasing section
15A acts as the heat releasing portion that releases and transmits
heat generated at the power conversion circuit unit 16 to the end
surface portion 15. In the present embodiment, a metal board of the
power conversion circuit unit 16 is welded to the protruding heat
releasing portions 28 by frictional stir welding, which securely
fixes the metal board to the protruding heat releasing portions
28.
[0074] As described above, in the present embodiment, a heat sink
member is not needed at the end surface portion 15 of the motor
housing 11, then a length in the axial direction can be shortened.
Further, since the motor housing 11 has a sufficient heat capacity,
it is possible to efficiently radiate or release heat of the power
supply circuit unit 17 and the power conversion circuit unit 16 to
the outside from the motor housing 11.
[0075] Next, FIG. 6 shows a state in which the power conversion
circuit unit 16 is mounted on the protruding heat releasing
portions 28 (see FIG. 4). As shown in FIG. 6, the power conversion
circuit unit 16 forming the redundant system is mounted on the
protruding heat releasing portions 28 (see FIG. 4) formed on the
power-conversion-circuit heat releasing section 15A. The switching
element forming the power conversion circuit unit 16 is mounted on
the metal board (using an aluminum-based metal), which is a good
heat radiation configuration. The metal board is welded to the
protruding heat releasing portions 28 by frictional stir
welding.
[0076] Thus, the metal board of the power conversion circuit unit
16 is firmly fixed to the protruding heat releasing portions 28,
and heat generated at the switching element can be efficiently
transmitted to the protruding heat releasing portions 28. Heat
transmitted to the protruding heat releasing portions 28 diffuses
through the power-conversion-circuit heat releasing section 15A,
and is further transmitted to the side peripheral surface portion
11A of the motor housing 11, then is released to the outside.
[0077] Here, as mentioned above, since a height of the
power-conversion-circuit heat releasing section 15A in the axial
direction is lower than that of the power-supply-circuit heat
releasing section 15B, the power conversion circuit unit 16 does
not interfere with the power supply circuit unit 17.
[0078] As described above, the power conversion circuit unit 16 is
mounted on the protruding heat releasing portions 28 formed on the
power-conversion-circuit heat releasing section 15A. Therefore,
heat generated at the switching element of the power conversion
circuit unit 16 can be efficiently transmitted to the protruding
heat releasing portions 28. Heat transmitted to the protruding heat
releasing portions 28 diffuses through the power-conversion-circuit
heat releasing section 15A, and is further transmitted to the side
peripheral surface portion 11A of the motor housing 11, then is
released to the outside.
[0079] Next, FIG. 7 shows a state in which the power supply circuit
unit 17 is mounted above or over the power conversion circuit unit
16. As shown in FIG. 7, the power supply circuit unit 17 is mounted
on the power-supply-circuit heat releasing section 15B. Capacitors
29 and coils 30 and so on which form the power supply circuit unit
17 are mounted on the glass epoxy circuit board 31. The power
supply circuit unit 17 has the redundant system, and as can be seen
from the drawings, power supply circuits configured by the
capacitors 29 and the coils 30 etc., which are arranged
symmetrically with respect to each other, are provided. The glass
epoxy circuit board 31 mounts thereon the electric elements such as
the capacitors, except the switching element of the power
conversion circuit unit 16.
[0080] A surface at the power-supply-circuit heat releasing section
15B side (see FIG. 6) of this glass epoxy circuit board 31 is fixed
to the end surface portion 15 so as to contact the
power-supply-circuit heat releasing section 15B. As a fixing
manner, as shown in FIG. 7, the glass epoxy circuit board 31 is
fixed to the screw holes provided at the board receiving portions
27 of the board-connector fixing protrusions 26 with fixing screws
(not shown), and also fixed to the screw holes provided at the
power-supply-circuit heat releasing section 15B (see FIG. 6) with
fixing screws (not shown).
[0081] Here, since the power supply circuit unit 17 is formed by
the glass epoxy circuit board 31, the circuit units could be
mounted on both sides of the glass epoxy circuit board 31. On the
surface at the power-supply-circuit heat releasing section 15B side
of the glass epoxy circuit board 31, the GMR element (not shown) or
a rotation phase and rotation speed detection unit that is
configured by a detection circuit formed by the GMR element is
mounted, and detects the rotation phase and the rotation speed of
the rotation shaft 23 (see FIG. 5) in cooperation with the rotation
detection portion 24 (see FIG. 5) provided at the rotation shaft
23.
[0082] As described above, since the glass epoxy circuit board 31
is fixed to the end surface portion 15 so as to contact the
power-supply-circuit heat releasing section 15B, it is possible to
efficiently transmit heat generated at the power supply circuit
unit 17 to the power-supply-circuit heat releasing section 15B.
Heat transmitted to the power-supply-circuit heat releasing section
15B is further transmitted to and diffuses through the side
peripheral surface portion 11A of the motor housing 11, then is
released to the outside. Here, by interposing one of a good heat
transfer adhesive (or a good thermal conductive adhesive), a heat
transfer grease (or a thermal conductive grease) and a heat
transfer sheet (or a thermal conductive sheet) between the glass
epoxy circuit board 31 and the power-supply-circuit heat releasing
section 15B, a heat transfer performance (or a thermal
conductivity) can be further improved.
[0083] As described above, the power supply circuit unit 17 is
mounted on the power-supply-circuit heat releasing section 15B. The
surface at the power-supply-circuit heat releasing section 15B side
of this glass epoxy circuit board 31 on which the circuit elements
of the power supply circuit unit 17 are mounted is fixed to the end
surface portion 15 so as to contact the power-supply-circuit heat
releasing section 15B. It is therefore possible to efficiently
transmit heat generated at the power supply circuit unit 17 to the
power-supply-circuit heat releasing section 15B. Heat transmitted
to the power-supply-circuit heat releasing section 15B is further
transmitted to and diffuses through the side peripheral surface
portion 11A of the motor housing 11, then is released to the
outside.
[0084] Next, FIG. 8 shows a state in which the control circuit unit
18 is mounted above or over the power supply circuit unit 17. As
shown in FIG. 8, the control circuit unit 18 is mounted above or
over the power supply circuit unit 17. Microcomputers 32 and
peripheral circuits 33 which form the control circuit unit 18 are
mounted on the glass epoxy circuit board 34. The control circuit
unit 18 also has the redundant system, and as can be seen from the
drawings, control circuits configured by the microcomputers 32 and
the peripheral circuits 33, which are arranged symmetrically with
respect to each other, are provided. The microcomputers 32 and the
peripheral circuits 33 could be mounted on a surface at the power
supply circuit unit 17 side of the glass epoxy circuit board
34.
[0085] This glass epoxy circuit board 34 is fixed to the screw
holes provided at tops of the board-connector fixing protrusions 26
(see FIG. 7) with fixing screws (not shown) so as to be sandwiched
by the connector terminal assembly 13, as shown in FIG. 8, then a
space in which the capacitors 29 and the coils 30 etc. of the power
supply circuit unit 17 shown in FIG. 7 are arranged is provided
between the glass epoxy circuit board 31 of the power supply
circuit unit 17 and the glass epoxy circuit board 34 of the control
circuit unit 18.
[0086] Next, FIG. 9 shows a state in which the connector terminal
assembly 13 is mounted above or over the control circuit unit 18.
As shown in FIG. 9, the connector terminal assembly 13 is mounted
above or over the control circuit unit 18. The connector terminal
assembly 13 is fixed to the screw holes provided at the tops of
board-connector fixing protrusions 26 with fixing screws 36 so as
to sandwich the control circuit unit 18 between the power supply
circuit unit 17 and the connector terminal assembly 13. In this
state, as shown in FIG. 3, the connector terminal assembly 13 is
connected to the power conversion circuit unit 16, the power supply
circuit unit 17 and the control circuit unit 18.
[0087] Further, after fixing the connector terminal assembly 13,
the opening end 37 of the metal cover 12 is engaged with the step
portion 35 of the motor housing 11, and fixed to the motor housing
11 at the fixing region FR provided in the outer circumferential
direction by the caulking or swaging fixation. As mentioned above,
the annular step portion 35 as the motor housing side annular
engagement portion formed at the outer circumferential surface of
the end surface portion 15 and the opening end 37 of the metal
cover 12 as the metal cover side annular engagement portion are
engaged with each other by fixation called a centering location
engagement (or an exactly-fitting engagement) or a centering
location fitting (or an exact fitting). However, a slight gap could
be allowed between the annular step portion 35 as the motor housing
side annular engagement portion and the opening end 37 as the metal
cover side annular engagement portion. Next, the fixing region FR
by the caulking or swaging fixation will be explained with
reference to FIGS. 10 to 14.
[0088] FIG. 10 shows an outward appearance of the electric power
steering device 6 with the motor housing 11 and the metal cover 12
fixed by the caulking or swaging fixation. FIG. 11 is a cross
section, cut in the axial direction, of the electric power steering
device 6 shown in FIG. 10.
[0089] The annular fixing region FR of the metal cover 12 is
provided with a plurality of caulk-fixing portions (or a plurality
of swage-fixing portions) 38. These caulk-fixing or swage-fixing
portions 38 are formed by deformation of a wall surface of the
metal cover 12 by pressing and squeezing, with a pressing tool, the
wall surface of the metal cover 12 against and into caulking
recessed portions (or swaging recessed portions) 40 formed by
caulking grooves (or swaging grooves) or caulking holes (or swaging
holes) that are formed at a fixing wall 39 extending from the
annular step portion 35 formed at the end surface portion 15 of the
motor housing 11 toward the connector terminal assembly 13 side in
the axial direction.
[0090] Further, a space G (see FIG. 13) formed by and between the
opening end 37 of the metal cover 12 and a wall surface extending
from the annular step portion 35 to the fixing wall 39 is filled
with a liquid sealant 41 to ensure liquid-tightness without any
gap. Therefore, since a liquid-tightness sealing region SR is
formed between the fixing region FR and the opening end 37 of the
metal cover 12, salt water etc. are prevented from getting inside
by and at the sealing region SR. Hence, since the saltwater etc. do
not get in the caulk-fixing portions 38 of the fixing region FR,
rust of the caulk-fixing portions 38 is suppressed, then mechanical
reliability can be improved. In addition, since the salt water etc.
are prevented from getting in the electronic control unit 9,
electrical reliability can also be improved.
[0091] Next, a detailed structure of the caulk-fixing portion 38
shown in FIG. 3.1 will be explained with reference to FIGS. 12 to
14.
[0092] In FIGS. 12 and 13, the opening end 37 of the metal cover 12
is engaged with the step portion 35 formed at an outer
circumferential end of the side peripheral surface portion 11A of
the motor housing 11 by the exactly-fitting engagement so as to
face each other. In this case, an outer peripheral shape, which
forms the step portion 35, of the side peripheral surface portion
11A of the motor housing 11 and an outer peripheral shape of the
opening end 37 of the metal cover 12 match up with each other.
Thus, in an engagement state of these step portion 35 and opening
end 37, an outer peripheral surface of the side peripheral surface
portion 11A and an outer peripheral surface of the opening end 37
of the metal cover 12 are flush with each other, and the outer
peripheral surface of the side peripheral surface portion 11A
continues to the outer peripheral surface of the opening end 37 of
the metal cover 12.
[0093] The caulking recessed portion 40 formed by the caulking
groove or the caulking hole is provided at the fixing wall 39
extending from the step portion 35 toward the connector terminal
assembly 13 side in the axial direction. Then, by pressing and
squeezing the wall surface of the metal cover 12 against and into
the caulking recessed portion 40 and deforming the wall surface of
the metal cover 12 with the pressing tool, the caulk-fixing portion
38 is formed. Regarding the caulking recessed portion 40, it could
be a seamless annular caulking groove formed on an outer peripheral
wall surface of the fixing wall 39 or a caulking groove having a
predetermined length in a circumferential direction. Instead, the
caulking hole could be arranged at necessary positions on the outer
peripheral wall surface of the fixing wall 39.
[0094] In the present embodiment, the caulking grooves each having
the predetermined length in the circumferential direction are
provided at necessary positions (three positions). Then, by the
wall surface of the metal cover 12 pressed against and squeezed
into these caulking recessed portions 40, movement of the metal
cover 12 in a rotation direction and in an axial direction of the
rotation shaft 23 with respect to the motor housing 11 is
suppressed.
[0095] As shown in FIG. 14, a cross sectional shape, orthogonal to
the axial direction, of the end surface portion 15 of the motor
housing 11 is broadly formed by round sections 11R and a
straight-line section 11S. Likewise, the opening end 37 of the
metal cover 12 is formed so as to match up with this cross
sectional shape. As shown by three bold arrows in the drawing, the
caulk-fixing portions 38 are formed around the middle of the
straight-line section 11S and at the round sections 11R located
symmetrically with respect to an extending line LE that connects
the middle of the straight-line section 11S and the rotation shaft
23.
[0096] Further, the space G formed throughout the entire
circumference between an inner peripheral wall surface of the
opening end 37 of the metal cover 12 and the wall surface extending
from the annular step portion 35 to the fixing wall 39 is filled
with the liquid sealant 41 to ensure liquid-tightness without any
gap. When performing the caulking or swaging fixation, first, the
liquid sealant 41 is applied, then the caulking or swaging fixation
is performed. Therefore, the sealing region SR is formed at the
opening end 37 side of the metal cover 12 when viewed from the
caulk-fixing portion 38 provided at the fixing region FR.
[0097] If a thickness of the liquid sealant 41 is thin, the liquid
sealant 41 might fall off. To prevent this fall-off, as shown in
FIG. 13, an annular groove 39G that is recessed to an inner
circumferential side is formed between the fixing wall 39 and the
step portion 35, and after filling this annular, groove 39G with
the liquid sealant 41, by pressing and squeezing the wall surface
of the metal cover 12 against and into the caulking recessed
portions 40 and deforming the wall surface of the metal cover 12,
the caulking or swaging fixation is performed. With this, a
sufficient thickness of the liquid sealant 41 is secured, then the
fall-off of the liquid sealant 41 can be suppressed.
[0098] Further, the liquid sealant 41 is applied to butting
surfaces of the opening end 37 of the metal cover 12 and the step
portion 35 of the end surface portion 15 of the motor housing 11,
to the outer peripheral surface of the opening end 37 of the metal
cover 12 and to an outer peripheral surface of the step portion 35
of the end surface portion 15 of the motor housing 11. With this
application of the liquid sealant 41, a liquid-tightness effect is
further increased. In particular, on the outer peripheral surface
of the opening end 37 of the metal cover 12 and at an exposed
portion 41A of the liquid sealant 41 which is formed on the outer
peripheral surface of the step portion 35 of the end surface
portion 15 of the motor housing 11, since a slit formed by the
butting surfaces of the opening end 37 of the metal cover 12 and
the step portion 35 of the end surface portion 15 of the motor
housing 11 is covered and filled with the liquid sealant 41, the
salt water etc. can be effectively prevented from getting
inside.
[0099] As the liquid sealant 41 to ensure liquid-tightness,
synthetic resin having adhesiveness is used. In the present
embodiment, an elastic silicon-based elastic adhesive is used. The
elastic silicon-based elastic adhesive has properties of absorbing
external vibrations and a stress by impact, which suppresses
concentration of the stress on bonding interfaces. Therefore,
although there is a risk that the liquid sealant 41 will fall off
from the bonding interfaces then liquid-tightness performance will
be lost for the electric power steering device that suffers from
the vibrations and the impact, by using the elastic silicon-based
elastic adhesive, the risk of losing the liquid-tightness
performance can be reduced. In addition, in the present embodiment,
since sealing is performed with the liquid sealant 41 having
adhesiveness, an O-ring conventionally used for the
liquid-tightness can be omitted. Therefore, there is no need to
form an accommodating groove for accommodating the O-ring at the
fixing wall 39, then increase in manufacturing cost can be
suppressed.
[0100] The elastic silicon-based elastic adhesive (the liquid
sealant) 41 could be replaced with a liquid gasket (FIPG: FORMED IN
PLACE GASKET) having adhesive performance, and the liquid gasket
made of room temperature hardening material or heat hardening
material can be used. With this, the salt water can be prevented
from getting inside from the engagement portion between the opening
end 37 of the metal cover 12 and the end surface portion 15 of the
motor housing 11.
[0101] Thus, since the salt water etc. are prevented from getting
inside by and at the sealing region SR before reaching the fixing
region FR, rust of the caulk-fixing portion 38 can be suppressed,
and decrease in fixing force (fixing strength) to fix the metal
cover 12 and the motor housing 11 is suppressed, then the
mechanical reliability can be improved. Also, since the salt water
etc. are prevented from getting in the electronic control unit 9,
the electrical reliability can also be improved.
[0102] Further, since the metal cover 12 and the motor housing 11
are fixed by the caulking or swaging fixation without using the
fixing screw, it is possible to reduce the outward appearance size
and the weight. In addition, in a case where the O-ring is used, it
is required to form the accommodating groove for accommodating the
O-ring. However, in the present embodiment, since the O-ring is not
used, no machining for the accommodating groove is required, and
this can suppress increase in manufacturing cost.
[0103] Here, if a liquid sealant 41 having a high heat radiation
performance, into which a good thermal conductive material such as
alumina is mixed, is used, because of a large bonding area of the
sealing region SR, heat of the power-conversion-circuit heat
releasing section 15A and the power-supply-circuit heat releasing
section 15B can be efficiently released to the metal cover 12. It
is therefore possible to efficiently release heat from the
electrical components forming the power supply circuit unit and the
power conversion circuit unit to the outside, and the size
reduction can be achieved.
[0104] In the present embodiment described above, as the fixing
manner to fix the metal cover 12 and the motor housing 11 without
using the fixing screw, the caulk-fixing portions 38 are provided
at the three positions. However, the caulk-fixing portion(s) 38
could be formed throughout the entire circumference. In addition,
instead of the caulking or swaging fixation, as a fixing manner
without using the fixing screw, the opening end 37 of the metal
cover 12 is press-fixed onto the fixing wall 39 of the step portion
35 of the motor housing 11, or the opening end 37 of the metal
cover 12 is fixed to the fixing wall 39 of the step portion 35 of
the motor housing 11 by shrink-fitting fixation.
Second Embodiment
[0105] Next, a second embodiment will be explained below. As a
different point from the first embodiment, in the present
embodiment, a coming-off prevention function is added to the
caulk-fixing portion 38 shown in the first embodiment, Other
structures or configurations of the present embodiment are the same
as those of the first embodiment. Therefore, their redundant
explanation will be omitted.
[0106] In FIGS. 15 and 16, at least two cutting portions 42 are
formed at the opening end 37 of the metal cover 12 according to a
length in the circumferential direction of the caulking recessed
portion 40. The opening end 37 between these two cutting portions
42 becomes a bending portion 43, and this bending portion 43 is
bent so as to hold the fixing wall 39 and engaged with the fixing
wall 39 between the caulking recessed portion 40 and the annular
groove 39G. That is, the bending portion 43 is engaged with a wall
surface of the annular groove 39G by being bent. In this case, the
caulk-fixing portion 38 and the bending portion 43 are formed at
the same time by undergoing working or machining at once with the
pressing tool. In the present embodiment, the bending portion 43 is
provided according to the number of the caulking recessed portion
40.
[0107] Therefore, the metal cover 12 is fixed to the motor housing
11 more firmly by this bending portion 43. In addition, the
coming-off prevention function that prevents the metal cover 12
from coming off in the axial direction is improved by the bending
portion 43.
[0108] Here, in the second embodiment, the motor housing 11 and the
end surface portion 15 are separately formed, and these motor
housing 11 and end surface portion 15 are fixedly connected with
fixing bolts or by welding. However, in the same manner as the
first embodiment, the motor housing 11 and the end surface portion
15 could be formed integrally with each other.
[0109] Further, in the present embodiment, the bending portion 43
is formed at the opening end 37 of the metal cover 12 according to
the length in the circumferential direction of the caulking
recessed portion 40 by the two cutting portions 42. However, the
bending portion 43 is not limited to this. Regardless of a forming
position of the caulking recessed portion 40, the arbitrary number
of the bending portion 43 could be formed at arbitrary positions at
the opening end 37 of the metal cover 12.
[0110] Also in the present embodiment, in the same manner as the
first embodiment, since the salt water etc. are prevented from
getting inside by and at the sealing region SR before reaching the
fixing region FR, rust of the caulk-fixing portion 38 can be
suppressed, and decrease in fixing force (fixing strength) to fix
the metal cover 12 and the motor housing 11 is suppressed, then the
mechanical reliability can be improved. Also, since the salt water
etc. are prevented from getting in the electronic control unit 9,
the electrical reliability can also be improved.
[0111] Further, since the metal cover 12 and the motor housing 11
are fixed by the caulking or swaging fixation without using the
fixing screw, it is possible to reduce the outward appearance size
and the weight. In addition, in a case where the O-ring is used, it
is required to form the accommodating groove for accommodating the
O-ring. However, in the present embodiment, since the O-ring is not
used, no machining for the accommodating groove is required, and
this can suppress increase in manufacturing cost.
Third Embodiment
[0112] Next, a third embodiment will be explained below. As a
different point from the first embodiment, in the present
embodiment, instead of the caulk-fixing portion 38 shown in the
first embodiment, the metal cover 12 and the motor housing 11 are
fixed by press-fitting or shrink-fitting. Other structures or
configurations of the present embodiment are the same as those of
the first embodiment. Therefore, their redundant explanation will
be omitted.
[0113] In FIG. 17, an annular accommodating groove 44 is formed at
an outer circumferential side of the step portion 35 of the motor
housing 11, and a side wall 45 is formed at an outer
circumferential side of the accommodating groove 44. The opening
end 37 of the metal cover 12 is firmly fixed to the wall surface of
the fixing wall 39 and an inner circumferential side wall surface
of the accommodating groove 44 by press-fitting or shrink-fitting.
The opening end 37 of the metal cover 12 is accommodated in the
accommodating groove 44, and the liquid sealant 41 fills the
accommodating groove 44 so as to encircle the opening end 37 from
outside.
[0114] Here, also in the third embodiment, the motor housing 11 and
the end surface portion 15 are separately formed, and these motor
housing 11 and end surface portion 15 are fixedly connected with
fixing bolts or by welding. However, in the same manner as the
first embodiment, the motor housing 11 and the end surface portion
15 could be formed integrally with each other,
[0115] Also in the present embodiment, in the same manner as the
first embodiment, since the salt water etc. are prevented from
getting inside by and at the sealing region SR before reaching the
fixing region FR, rust of the caulk-fixing portion 38 can be
suppressed, and decrease in fixing force (fixing strength) to fix
the metal cover 12 and the motor housing 11 is suppressed, then the
mechanical reliability can be improved. Also, since the salt water
etc. are prevented from getting in the electronic control unit 9,
the electrical reliability can also be improved.
[0116] Further, since the metal cover 12 and the motor housing 11
are fixed by the caulking or swaging fixation without using the
fixing screw, it is possible to reduce the outward appearance size
and the weight. In addition, in a case where the O-ring is used, it
is required to form the accommodating groove for accommodating the
O-ring. However, in the present embodiment, since the O-ring is not
used, no machining for the accommodating groove is required, and
this can suppress increase in manufacturing cost.
[0117] As described above, the present invention has the motor
housing side annular engagement portion formed on the outer
circumferential surface of the end surface portion of the
metal-made motor housing which is the opposite side to the output
shaft portion of the rotation shaft of the electric motor; and the
metal cover side annular engagement portion formed at the opening
end of the metal cover that covers the electronic control unit
configured to control the electric motor and engaged with the motor
housing side annular engagement portion. And, the fixing region is
formed by fixing the metal cover side annular engagement portion to
the motor housing side annular engagement portion in the fixing
manner without using any fixing screw in a state in which the metal
cover side annular engagement portion is engaged with the motor
housing side annular engagement portion, and the sealing region is
formed between the fixing region and the opening end of the metal
cover with a liquid sealant applied between the fixing region and
the opening end of the metal cover.
[0118] According to this configuration, since the sealing region is
formed between the fixing region and the opening end of the metal
cover with the liquid sealant applied between the fixing region and
the opening end of the metal cover, salt water etc. are prevented
from getting in the fixing region, then mechanical and electrical
reliability can be improved. Further, since the fixing screw is not
used, it is possible to reduce an outward appearance size and a
weight.
[0119] The present invention is not limited to the above
embodiment, and includes all design modifications. The above
embodiment is an embodiment that is explained in detail to easily
understand the present invention, and the present invention is not
necessarily limited to the embodiment having all elements or
components described above. Further, a part of the configuration of
the embodiment can be replaced with a configuration of other
embodiments. Also, the configuration of other embodiments could be
added to the configuration of the embodiment. Moreover, regarding a
part of the configuration of the embodiment, the configuration of
other embodiments could be added, removed and replaced.
* * * * *